Various wind turbine related arrangements have been suggested in order to deal with so-called Low Voltage Ride Through (LVRT) events—cf. for example US 2007/0164567 and US 2007/0279815. The suggested arrangements are both full-scale power conversion arrangements where all the electrical power generated by a generator is passed through a generator side converter and a grid side inverter, the converter and the inverter being separated by an intermediate DC circuit.
During a LVRT event, the amount of power to be fed into a power supply grid has to be reduced due to the current ratings of the grid side inverter. Since sufficient energy can normally not be stored in the converter system, the power captured from the wind has to be reduced accordingly or, alternatively, the excess of power has to be dissipated. The latter solution has many advantages—e.g. the tear and wear on the mechanical parts of the wind turbine facility can be reduced significantly. Moreover, the wind turbine facility can be brought into power production very fast after the LVRT event has disappeared.
The power dissipating device has to be thermally designed for the desired amount of energy to be dissipated. Moreover, since the power dissipating device will require a relatively long time to cool down the number of successive low voltage events will also be a challenging design parameter.